docs: def datetime2et(dt):
      """
      Converts a standard Python datetime to a double precision value 
      representing the number of TDB seconds past the J2000 epoch 
      corresponding to the input epoch.
  
      https://naif.jpl.nasa.gov/pub/naif/toolkit_docs/C/req/time.html#The%20J2000%20Epoch
  
      :param dt: A standard Python datetime
      :type time: datetime
      :return: The equivalent value in seconds past J2000, TDB.
      :rtype: float
      """
      lt = ctypes.c_double()
      if hasattr(dt, "__iter__"):
          ets    = []
          for t in dt:
              libspice.utc2et_c(stypes.stringToCharP(t.isoformat()),ctypes.byref(lt))
              checkForSpiceError(None)
              ets.append(lt.value)
          return ets
      dt = stypes.stringToCharP(dt.isoformat())
      et = ctypes.c_double()
      libspice.utc2et_c(dt, ctypes.byref(et))
      return et.value